1. Technical Field
The present invention relates generally to a semiconductor device, and more particularly to a semiconductor memory device capable of protecting blocks.
2. Related Art
In general, a semiconductor memory device is classified into a volatile memory device and a nonvolatile memory device. The volatile memory device requires power to maintain data stored therein, but the semiconductor memory device maintains data stored therein even in absence of the power.
A memory system including the semiconductor memory device such as the nonvolatile memory device may not operate normally when data stored in the semiconductor memory device are unexpectedly changed. Therefore, the memory system including the semiconductor memory device requires a function of protecting data stored in the semiconductor memory device so that the data are not unexpectedly changed. For example, when the memory system is booted up, the semiconductor memory device may enter a lock state so that the data stored therein are not changed. The lock state means a state of the semiconductor memory device (e.g., nonvolatile memory device), in which a program operation or erase operation is not performed.
The semiconductor memory device may enter a protection mode (e.g., the lock state) through various methods. For example, the semiconductor memory device may enter the lock state according to a command provided from outside. As another example, the semiconductor memory device may enter the lock state according to a specific signal inputted through a physical pin.